As materials for magnetic shielding parts and magnetic core elements represented by cores of clocks, small size transformers, etc., alloys of JIS-PB, JIS-PC alloys and Fe-Ni(Mo, Cu) alloys and Fe-Ni-Cr alloys are widely used.
Usually these magnetic alloy materials are subjected to magnetic annealing after they have been shaped for imparting good magnetic characteristics. Magnetic annealing is effected in a hydrogen atmosphere at a high temperature of 900.degree.-1200.degree. C. for a prolonged time of 0.5-2 hours. In magnetic annealing, there is a problem that parts stick to each other during annealing when a large number of parts are treated at one time. Therefore, the parts are embedded in a large amount of alumina powder to prevent adhesion in the conventional technique.
Nowadays a larger number of parts are treated at one time and use of a large amount of alumina powder causes problems such as the need for separation by screening and rinsing of the treated parts, which invites increase in the production cost. Screening and rinsing operations cause strain in the treated parts, which degrades magnetic properties of the parts. Therefore, there is a strong demand for improvement in the method of magnetic annealing when reduction of production cost, down-sizing of parts and improvement in performance of products are imperative in the electronic magnetic industry. The present invention aims at eliminating the need for the alumina powder when the Fe-Ni, Fe-Ni-Mo, Fe-Ni-Cr alloy parts are subjected to magnetic annealing after shaped.